chapter 2 natural selection and reproductionchucklumio.com/amplify lesson...

CHAPTER 2 – NATURAL SELECTION AND REPRODUCTION

2.2.1: WARM-UP

1. What do you notice about the traits of the offspring

compared to the parents?

2. Where do organisms get their traits?

The traits of the offspring are similar to the parents.

Genes are passed on from parent to offspring. Genes

are instructions for making protein molecules. Protein

molecules are what give organisms their traits.

Share your observations of the offspring compared with the

parents.

• The traits of the offspring are similar, but not identical, to

those of the parents.

We will further investigate where individuals in populations

get their traits using a spider simulation.

We are going to begin our lesson today looking at another kind of organism and explore a

model of how individuals in a population get their traits. We will be focusing on the feature of

stripe color in a population of spiders.

Yesterday we read about glowing jellies

and the protein molecule that leads to

that trait.

2.2.1: WARM-UP

Project the Traits and Reproduction SIM

Let’s focus on and identify Otis and Ruby’s traits

• Otis is brown with a blue stripe and a little bristle

(hair),

• Ruby is yellow with a black stripe and a lot of bristle

(hair)

We will look at their genes for stripe color and how they lead to protein molecules and

therefore traits.

Then we will look at their offspring to see how the traits were passed down.

2.2.1: WARM-UP

Investigate Otis and

Ruby’s genes and protein

molecules.

Select stripe color on the

top menu and then press

on Otis to show his cells.

Let’s look at Otis. This is a

model of his cells.

2.2.1: WARM-UP

These pink shapes are

protein molecules.

Notice that they fit together

with other molecules in the

cell and together they

produce blue pigment.

This is how protein

molecules lead to the blue

stripe trait.

2.2.1: WARM-UP

Genes are found on chromosomes

and there are two copies of every

gene.

These copies can be the same

version or different versions.

Otis has two of the same version,

T2.

This version of the gene gives the

cells the instructions to make the

protein molecules that lead to the

blue pigment.

2.2.1: WARM-UP

Press the X in the top right

corner and then press on Ruby.

Let’s look at Ruby.

On her chromosomes she also has

two copies of the gene for stripe

color, but her copies are not the

same.

She has two different versions, T2

and T3.

Different versions of a gene are also

called alleles.

2.2.1: WARM-UP

Notice that she has one version of

the gene that is the same as Otis.

The T2 gene gives the cells

instructions to make the protein

molecule that leads to blue pigment.

That is the protein molecule with a

rounded shape.

Ruby also has another version of the

gene, T3.

This is still the gene for stripe color, but the protein molecule that is produced is a different

shape, it is pointy instead of round. Because of its different shape it fits together with a different

molecule and produces black pigment instead. Black pigment mixed with blue pigment produces

a black color, so her stripe is black.

2.2.1: WARM-UP

Press the X in the top right corner and

then press on Otis again.

This simulation will allows us to change the

genes of Otis and see what happens to his

protein molecules.

In real life organisms cannot just change their

genes, but this is a model that can help us see

what happens when we change the genes.

What do you think will happen if I change one of his gene copies to T3, the same version that

Ruby had?

His cells will start to produce the pointy protein molecule and he will produce

black pigment and his stripe will turn black

2.2.1: WARM-UP

Change one of the genes to T3.

The cell now makes the rounded and pointy

protein molecules and therefore blue and

black pigment.

Now Otis’s stripe is black.

Change the genes back to T2 and T2.

Note that you are putting his gene back

the way they were.

Press the X in the top right corner to return to the starting screen.

2.2.1: WARM-UP

Drag Ruby and Otis together

If Otis and Ruby have offspring, what color

stripes do you think they will have?

• some blue and some black

Press SKIP TO OFFSPRING on the

bottom right. Some spiders have black

stripes and some have blue stripes.

2.2.1: WARM-UP

Press a spider with a blue stripe. Point out that this spider has two copies of the T2

version of the gene. One came from Otis and one came from Ruby.

Organisms get genes from their parents. Notice the protein molecules in the cell.

Genes are instructions for making protein molecules and that protein molecules lead to traits.

Press the X in the top right corner.

2.2.1: WARM-UP

Press a spider with a black stripe.

The spider has two different versions of the gene, T2 and T3.

T2 came from Otis and T3 came from Ruby.

The cell has instructions to make both protein molecules, so the cell produces black and blue

pigment. The stripe color is black.

2.2.1: WARM-UP

Summarize where individuals in population get their traits.

Organisms get their genes from their parents and the genes are instructions for making protein

molecules which lead to traits.

2.2.1: WARM-UP

Crosscutting concept of Structure and Function.

Point out that microscopic structures can be modeled to show how their

function depends on their shapes.

As we saw in the Sim, the structure—or shape—of the protein molecule

determines its function, or what that protein molecule does.

The rounded protein molecule only fit together with a certain molecule,

which lead to the production of blue pigment.

The pointy protein molecule only fit together with a different molecule,

which lead to the production of black pigment.

2.2.1: WARM-UP

Chapter 2 Question:

How did the trait for increased poison level become more common in the newt population?

Now that we know where individuals in populations get their traits, we can continue to think

about how the trait for poison level became more common in the newt population.

2.2.2: SIM

At the end of chapter 1 the class agreed that the newt population became more poisonous because the

snakes in this environment caused poison to be an adaptive trait, but now some park visitors are

offering additions to the claim.

Some park visitors have offered two competing ideas.

• Some park visitors have suggested that Poison Level 10 is the most common because

newts with this trait live longer than other newts.

• Others think that Poison Level 10 is the most common because newts with this trait

reproduce more than other newts.

Each of these ideas builds on the claim we decided to support at the end of Chapter 1, but

now we need to figure out which one is best supported by evidence.

2.2.2: SIM

Discuss the claim additions…

Do you agree or disagree with the claims - share your ideas with your partner.

2.2.2: SIM

Investigation Question

How do some traits become more common over many generations while others

become less common?

To be able to support one of these claims we

need to understand why traits become more

common in a population.

In previous activities, we looked at how

offspring get genes from their parents when

organisms reproduce.

Genes are instructions for making protein

molecules that determine an individual’s traits.

2.2.2: SIM

How is it possible then that some traits can

become more common over many generations

while others become less common over many

generations?

Shouldn’t each generation match the generation

before it?

Discuss your ideas about the investigation

question with a partner.

The next activity will provide evidence to help

you better answer this investigation question.


How do some traits become more common over many generations while others

become less common?

2.2.2: SIM

Some organisms reproduce more than

others.

Let’s review possible answers to the Investigation

Question.

• Some organisms can have more offspring than

others.

• Some organisms will not survive in the

environment long enough to reproduce.

If yellow ostrilopes from one generation had

more offspring than green ostrilopes, would the

next generation have more yellow ostrilopes

than green ostrilopes?

YES

2.2.2: SIM

Introduce the Sim activity.

You will use the Sim to gather evidence about whether ostrilopes with adaptive traits have

more offspring than ostrilopes with non-adaptive traits.

Let’s establish which traits are adaptive.

The environment color for this Sim activity is

Yellow 7 and there will be carnithons present

in the environment.

Which color trait is most adaptive in this

environment?

Yellow 7

2.2.2: SIM

Our Sim mimics the natural world, which is

very complex.

Like the natural world, random events can

occur in the Sim world that could make it

difficult to draw conclusions if we don’t collect

enough data.

For example, some ostrilopes might randomly

have more opportunities to reproduce than

others.

2.2.2: SIM

By collecting enough data, we’ll be able to

determine if the data shows a pattern that

is not due to random events.

So, we are each going to collect data and then

use all of it in a class data set.

By averaging all our data, we might be able to

find a pattern to show us which ostrilopes tend

to have the most opportunities to reproduce.

2.2.2: SIM

Using the Reproduction Claims mode let’s zoom in and demonstrate locating an ostrilope

with a color trait from the data table on your screen (Blue 1, Blue 4, Yellow 7, Yellow 10).

Let’s Project the Natural Selection Simulation and demonstrate collecting data

and resetting the Sim.

2.2.2: SIM

https://apps.learning.amplify.com/naturalselection/

In previous Sim activities, we were

looking for changes over time, so we

watched a whole population for many

generations.

In this Sim activity, we are looking at

individuals.

When the individual you are following

dies, you will need to reset the Sim and

choose another individual to observe

from the beginning.

2.2.2: SIM

Select that ostrilope and press RUN.

Count the number of times that ostrilope reproduces, and record that number in the data

table. Reset the Sim to collect data for a different ostrilope color.

Let’s Project the Natural Selection Simulation and demonstrate collecting data

and resetting the Sim.

Record the number of

times the ostrilope

Reproduces

Reset SIM after each ostrilope dies.

2.2.2: SIM

https://apps.learning.amplify.com/naturalselection/

2.2.2: SIM

We gathered information about the number

of offspring for each color trait in the data

table.

But, following just a few ostrilopes before

they die is not enough for us to identify a

pattern at the scale of the population.

To do this, we need to compare

observations from the whole class and

come to a group conclusion about what we

see.

We’ll need to collect data from each group

and average it.

Collecting whole class data using the DATA TOOL

2.2.2: SIM

Let’s share what you notice from the

data tool

Observe the following:

• Not all ostrilopes reproduced the same

amount.

• Ostrilopes with adaptive traits (Yellow

Color 7) reproduced more on average

(because they were the most likely to

survive).

• Ostrilopes with non-adaptive traits

(Levels 1, 4, and 10) reproduced less on

average (because they were less likely to

survive as long).

2.2.2: SIM

Discuss with your table how this averaged data from the class helps to answer the


2.2.2: SIM

1. What pattern describes the relationship between how long an ostrilope lived and how many offspring it had?

2. Which ostrilopes became more common over time, and why?

3. Which ostrilopes became less common over time, and why?

4. If the color of the environment became blue, which ostrilopes do you think would become more or less

common, and why?

Ostrilopes that lived longer had more offspring.

Ostrilopes with Yellow Color 7 became more common because they survived longer, so they had more

opportunities to reproduce and have offspring.

Ostrilopes with colors that didn’t blend into the environment, like Blue Color 1, 4, and Yellow Color 10, became less

common because they were more likely to be eaten by predators before they could have many offspring.

Ostrilopes with blue-color traits would become more common because they’d be camouflaged and survive longer, so

they could have more offspring. Ostrilopes with green and yellow colors would be more likely to be eaten by

carnithons before they could have many offspring.

2.2.2: SIM

Answer the poll by selecting your choice at the bottom of .

Supports: ostrilopes with Yellow Color 7

had a higher average then the others.

VIEW POLLING DATA

2.2.2: SIM

2.2.3: MODELING TOOL

You will create a model to explain how different organisms’ survival and

reproduction rates lead to traits becoming more or less common over time.GOAL

You will be using the Modeling Tool

to respond to Sherman.

Scientists often explain their

thinking in writing and by making

visual models.

You are going to return to

the Sherman’s Story from the

previous lesson and explain your

thinking by writing a response and

making a visual model.

You will create a model to explain how different organisms’ survival and

reproduction rates lead to traits becoming more or less common over time.GOAL

Reread the Sherman’s

Story independently.

This is the same story you saw in

the Warm-Up in Lesson 2.1, but

this time there is some new text in

the last panel.


NEW TRAIT

LABELS

You will make a

model of how the

distribution of beak-

strength traits

changed.

This model will help

you write your

responses to

Sherman.

You can add more

than one Trait label

to a single trait.

Add trait

labels

Predict

Histogram


Respond to Prompt after creating

your visual model.

1 2

3


Modeling Tool Response:

A proficient model is shown below. You should group the Trait labels together as shown in Histogram 1 (+S

with +O, -S with -O). Proficient models should include at least two traits labeled in Histogram 1 but might

include all traits labeled. Predictions about Histogram 2 will vary significantly. Correct responses should show a

shift in distribution of traits toward stronger beak strength and should only include traits that were present in

Histogram 1.

TIME


WHY DO THESE BIRDS HAVE STRONGER BEAKS

TIME

Individuals get their traits from their parents.

The birds with stronger beaks

were able to crack open more

seeds and eat more, which

means they lived longer and

reproduced more, passing on

their strong-beak trait.

What may have happened is birds with weak beaks couldn’t crack enough seeds to have enough to eat to survive,

and so they died before they could reproduce, which means they did not pass on their weak-beak trait.

Over many generations, the

distribution of traits changed

so that the population had

more and more individuals

with the strong-beak trait.


Let’s share your responses to Sherman’s Story.

Connecting Sherman’s Story to the old claim that individual newts became more

poisonous because they wanted to.

In the Warm-Up, you read and thought about the claims regarding the newt mystery.

Based on Sherman’s Story that you just read, what else can we say to people who

think that the newts in Oregon State Park became more poisonous because they

wanted to?

That’s impossible. Traits are determined by protein

molecules that are determined by genes that are inherited

from an individual’s parents. Individuals cannot choose their

traits.


Example:

• We have been investigating how populations change over many generations.

• Most of these changes are in response to environmental changes.

• This is connected to what you learned about in the Microbiome unit.

• When one part of the body system changes, such as an increase in the number of harmful gut

bacteria, other body systems are affected.

• As a result, the other helpful bacteria in the intestines cannot survive, which makes people sick.

Think creatively!

Challenge yourself to connect a very

different science topic to our current topic.

chapter 2 natural selection and reproductionchucklumio.com/amplify lesson...

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